from Wiktionary, Creative Commons Attribution/Share-Alike License
- "No problem", "the solution is simple", "there you have it", you have what you want, all will be well; indicates a desirable conclusion has been reached.
Unknown - first printed usage from 1937. Several unsupported theories exist about its origin. A common explanation, involving Arthur Balfour gaining a promotion through the supposed intercession of his uncle Robert, seems unlikely given the expression was apparently not used before the late 1930s. (Wiktionary)